Method for preparing polyhydroxyalkanoate copolymer under catalysis of cyclopropene onium salt catalyst

Abstract

The method comprises the following steps: by taking a cyclic monomer or a cyclic monomer and a micromolecular monomer as substrates, carrying out polymerization reaction under the action of the cyclopropene onium salt catalyst as shown in a formula (I), so as to prepare the polyhydroxyalkanoate polymer, the cyclic monomer at least comprises beta-lactone of a four-membered ring. The cyclopropene onium salt organic catalyst with ion pair tension provided by the invention has the advantages of high catalytic activity, controllable reaction, no metal residue in a polymer, and high yield; compared with the prior art, the method has the advantages that the reaction rate is high, the conversion frequency TOF value can reach up to 990h <-1 >, the molecular weight of the obtained polymer can reach up to 216.7 kg / mol, and the molecular weight distribution # imgabs 0 # # imgabs 1 # is obviously improved and is obviously narrowed compared with the prior art. # imgabs2 #

Description

Technical Field

[0001] The invention relates to the field of catalysis, and in particular to the application of a cyclopropenium salt organic catalyst with ion pair tension in the preparation of polyhydroxy fatty acids and copolymers thereof by ring-opening polymerization. Background Art

[0002] As the oil crisis and environmental problems become increasingly prominent, the synthesis of biodegradable plastics has received more and more attention and research. Polyhydroxyalkanoates (PHAs) are a class of aliphatic polyesters that can be prepared by bacteria and other microorganisms using biorenewable energy sources such as carbohydrates and fats as raw materials. This type of polymer has good biodegradability, biocompatibility, thermal processability and gas barrier properties, and can be used in biomedicine, packaging materials, agricultural mulch films and other fields. Among them, poly (3-hydroxypropionic acid) (P3HP) is the simplest polyhydroxyalkanoate with a repeating -CH2- unit in its main chain structure. The high molecular weight P3HP has high toughness and tensile strength. Poly (3-hydroxybutyric acid) (P3HB) is the most widely studied type of polyhydroxyalkanoate in recent years. Its high crystallinity gives it a strength comparable to that of polypropylene, and it is expected to become a substitute for polypropylene. In addition, there are polyhydroxyalkanoates with short carbon chain side chains such as ethyl, propyl, and butyl.

[0003] At present, biological fermentation is the main method for preparing polyhydroxy fatty acids (such as patents CN103898034A, CN109504715A, etc.). However, the biological fermentation method requires strict reaction temperature, pH and highly sealed fermentation tanks. This method has high production costs, low polyhydroxy fatty acid yields and can only prepare random copolymers of polyhydroxy fatty acids. The chemical method of synthesizing polyhydroxy fatty acids by β-lactone ring-opening polymerization can not only prepare high molecular weight, narrow distribution polymers, but also prepare different copolymers such as random, block, gradient, etc. based on polyhydroxy fatty acids to adjust material properties to adapt to different application scenarios.

[0004] In the prior art, various catalysts have been developed and applied to the ring-opening polymerization of β-lactone to prepare PHA with high molecular weight and high stereoregularity. For example, Eugene Y.-X. Chen of Colorado State University in the United States developed a catalytic system based on rare earth metal Y to catalyze the ring-opening polymerization of BL dimer (8DL) to prepare PHB (M n =119kg / mol, )(Science 2019754–758), but the synthesis steps of 8DL monomer in this method are numerous, the overall yield is low, and the application prospect is small; Lv Xiaobing et al. from Dalian University of Technology developed the Salen-Co / MTBD catalytic system to catalyze the ring-opening polymerization of PL (CCS Chem. 2022344–355) to prepare PPL (M n =97.0kg / mol, ), but metal Co will seriously pollute the color of the polymer, increase production costs, and limit the application of polymers in the fields of biomedicine and microelectronics; the large steric hindrance organic phosphorus acetate developed by Geoffrey W. Coates can prepare P3HP with high molecular weight and narrow distribution, however, the catalyst preparation steps are many, the yield is low, and it is difficult to prepare high molecular weight polyester materials (ACS Catal. 20168219-8223); Huang Pengtao and others from Gaohua Co., Ltd. developed tetramethylammonium acetate, bistriphenylphosphonium imide acetate and other organic catalysts to catalyze the ring-opening polymerization of β-lactones such as BL and PL, but the catalyst conversion frequency is low and the molecular weight distribution of the resulting polymer is wide. (Patent CN114685764A). Therefore, it is still a challenge to develop an organic catalytic system with simple synthesis, high catalytic efficiency, the ability to prepare high molecular weight and narrow distribution PHAs, and no metal residue. Summary of the invention

[0005] The present invention aims at the shortcomings of traditional metal catalysts, such as high metal residue and complex preparation; at the same time, aims at the shortcomings of low catalytic efficiency, low prepared polymer molecular weight and wide distribution of current organic catalysts such as organic bases, quaternary ammonium salts or quaternary phosphonium salts, and provides a cyclopropene salt organic catalyst system with ion pair tension, which has the advantages of high activity, easy preparation and no metal residue, and is used for catalyzing the ring-opening polymerization of beta-lactone and copolymerizing with other monomers to prepare polyhydroxy fatty acid polymer materials, and the prepared polymer material has high molecular weight and narrow molecular weight distribution.

[0006] The technical solution provided by the present invention is:

[0007] A method for preparing polyhydroxyalkanoic acid polymers by catalyzing a cyclopropene salt catalyst, the method comprising:

[0008] A cyclic monomer or a cyclic monomer and a small molecule monomer are used as substrates, and a catalytic polymerization reaction is carried out under the action of a cyclopropene salt catalyst to prepare a polyhydroxy fatty acid polymer; the polyhydroxy fatty acid polymer includes polyhydroxy fatty acid, polyhydroxy fatty acid-polyether copolymer, polyhydroxy fatty acid-polythioester copolymer, polyhydroxy fatty acid-polycarbonate copolymer, polyhydroxy fatty acid-polypolypeptide copolymer, etc.;

[0009] The polymerization reaction includes ring-opening homopolymerization or ring-opening copolymerization. When the substrate is a single cyclic monomer, the polymerization reaction is ring-opening homopolymerization. When the substrate is a plurality of different cyclic monomers, or a cyclic monomer and other small molecular monomers, the polymerization reaction is ring-opening copolymerization.

[0010] The cyclic monomer at least includes a four-membered ring β-lactone, and its structural formula is shown in formula (III):

[0011]

[0012] Among them, R7, R9, R 10 Each independently selected from hydrogen, unsubstituted or having one or more substituents C: C1-C 18 Alkyl, C1-C 18 Ester group, C3-C 18 Cycloalkyl, C2-C 18 Alkenyl, C2-C 18 Alkynyl, C6-C 18 Aromatic, C3-C 18 Heterocyclic or C5-C 18 A heteroaromatic group;

[0013] The substituent C is a C1-C10 alkyl group, a C1-C10 alkoxy group, a C3-C10 cycloalkyl group, a C3-C10 heterocyclic group, a C5-C 10 The compound may be selected from the group consisting of a heteroaromatic group of C6 to C10 and an aromatic group of C6 to C10.

[0014] Preferably R7 is H, C1-C5 alkyl, C2-C5 alkenyl or phenoxycarbonyl;

[0015] Preferably R9, R 10 Each is independently hydrogen or C1-C5 alkyl.

[0016] R8 is selected from O, S or NH, preferably O.

[0017] The cyclic monomer represented by formula (III) may be a racemic, meso or enantiomerically pure monomer.

[0018] The β-lactone structural formula is preferably selected from the following structures:

[0019]

[0020] The cyclic monomer may also include a cyclic copolymer monomer, which includes one or more of oxiranes, cyclothioalkane, cyclic lactones with a ring size greater than four members, cyclic lactides, cyclic carbonates, cyclic anhydrides, O-carboxylic anhydrides, N-carboxylic anhydrides, and thio-N-carboxylic anhydrides.

[0021] The cyclic copolymer monomer preferably has the following structure:

[0022]

[0023] Among them, R 11 and R 12 Each is independently selected from the following groups which are unsubstituted or have one or more substituents D: C1-C 30 Alkylene, C3-C 30 Cycloalkylene, C2-C 30 Alkenylene, C2-C 30 Alkynylidene, C6-C 30 Aromatic, C3-C 30 Heterocyclic or C5-C 30 Heteroaromatic group, or the above group containing O, S, N, Si, P atoms in the carbon chain; the substituent D is halogen, a branched or straight chain hydrocarbon group with 1 to 20 carbon atoms, a branched or straight chain alkoxy group with 1 to 20 carbon atoms, a branched or straight chain cycloalkyl group with 3 to 20 carbon atoms, an aromatic group with 6 to 20 carbon atoms, or a heteroaromatic group with 5 to 20 carbon atoms;

[0024] Among them, R 13 Selected from H, halogen, unsubstituted or having one or more substituents E: C1-C 30 Alkyl, C3-C 30 Cycloalkyl, C2-C 30 Alkenyl, C2-C 30 Alkynyl, C6-C 30 Aromatic, C3-C 30 Heterocyclic or C5-C 30 The substituent E is one or more selected from halogen atoms, branched or straight-chain hydrocarbon groups having 1 to 20 carbon atoms, branched or straight-chain alkoxy groups having 1 to 20 carbon atoms, branched or straight-chain cycloalkyl groups having 3 to 20 carbon atoms, aromatic groups having 6 to 20 carbon atoms, and heteroaromatic groups having 5 to 20 carbon atoms.

[0025] Preferred R 11 , R 12 It is C1-C4 alkylene, C2-C3 alkenylene, C3-C6 cycloalkylene or phenyl.

[0026] Preferred R 13 It is H, halogen, C1-C5 alkyl, C2-C4 alkenyl, C3-C6 cycloalkyl or phenyl.

[0027] More preferably, the cyclic copolymerizable monomer may be one of the following:

[0028]

[0029] The small molecule monomer includes carbon dioxide or carbon monoxide;

[0030] The polymerization reaction of the present invention may be a self-polymerization reaction of a β-lactone or a copolymerization reaction of multiple β-lactones, or a copolymerization reaction of one or more β-lactones with a cyclic copolymer monomer and / or a small molecule monomer;

[0031] In the method, the chemical formula of the cyclopropene salt catalyst is as shown in formula (I):

[0032]

[0033] Among them, X - is a negative ion selected from F - , Cl - Br - ,I - 、NO3 - 、CH3COO - 、CCl3COO - CF3COO - 、Cl2CHCOO - 、PhCOO - , t BuCO - 、CH3CH=CHCOO - 、ClO4 - 、BF4 - ,BPh4 - 、N3 - OH - , p-toluenesulfonate, o-nitrophenoloxy, p-nitrophenoloxy, m-nitrophenoloxy, 2,4-dinitrophenoloxy, 3,5-dinitrophenoloxy, 2,4,6-trinitrophenoloxy, 3,5-dichlorophenoloxy, carbonate, bicarbonate, 3,5-difluorophenoloxy, 3,5-di-trifluoromethylphenoloxy or pentafluorophenoloxy anion or a combination of one or more thereof;

[0034] Y1 can be selected from N or P atoms;

[0035] R1 and R2 may be independently selected from the following groups which are unsubstituted or have one or more substituents A: hydrogen, C1-C 18 Alkyl, C3-C 18 Cycloalkyl, C2-C 18 Alkenyl, C2-C 18 Alkynyl, C6-C 18 Aromatic, C2-C 18 Heterocyclic or C5-C18 One or a combination of at least two of the heteroaromatic groups, or R1, R2 and Y1 atoms are connected to form a ring to form a heterocyclic group containing Y1; the substituent A can be one or more of a C1-C10 alkyl group, a C1-C10 alkoxy group, a C3-C10 cycloalkyl group, a C3-C10 heterocyclic group, a C5-C10 heteroaromatic group, and a C6-C10 aromatic group;

[0036] Preferably, R1 and R2 are independently C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C6-C 10 Aromatic or C5-C 10 Heteroaromatic group, or R1, R2 and Y1 atoms are connected to form a C2-C5 heterocycloalkyl group; more preferably, R1 and R2 are each independently a C1-C4 alkyl group, a C3-C6 cycloalkyl group, a phenyl group, a naphthyl group, a benzyl group, a pyridine group or a quinoline group; or R1, R2 and Y1 atoms are connected to form a C5 heterocycloalkyl group;

[0037] R1 and R2 may be the same substituent, or R1 may be H and R2 may not be H. R1 and R2 may not be H at the same time.

[0038] R3 can be selected from H, alkylamino (or phosphorus) group, aromatic amino (or phosphorus) group, (thio)urea group, and can be specifically selected from the following structures:

[0039]

[0040] Wherein, Y2 can be selected from N or P atoms; Z can be selected from O or S atoms; Y1 and Y2 can be the same or different;

[0041] n is an integer from 1 to 10;

[0042] R4, R5, and R6 may be independently selected from the following groups which are unsubstituted or have one or more substituents B: hydrogen, C1-C 18 Alkyl, C3-C 18 Cycloalkyl, C2-C 18 Alkenyl, C2-C 18 Alkynyl, C6-C 18 Aromatic, C2-C 18 Heterocyclic or C5-C 18 The substituent B may be a C1-C10 alkyl, a C1-C10 alkoxy, a C3-C10 cycloalkyl, a C3-C10 heterocyclic group, a C5-C 10One or more of heteroaromatic groups, C6-C10 aromatic groups;

[0043] Preferably, R4 and R5 are each independently H, C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C6-C 10 Aromatic or C5-C 10 Heteroaromatic group, or R4, R5 and Y2 atoms are connected to form a C2-C5 heterocycloalkyl group;

[0044] More preferably, R4 and R5 are each independently H, C1-C4 alkyl, C3-C6 cycloalkyl, phenyl, substituted phenyl, naphthyl, benzyl, pyridine or quinoline, and the substituent on the substituted phenyl is one or more of C1-C4 alkyl, halogen atom, trifluoromethyl; or R4, R5 and Y2 atom are connected to form a C5 heterocycloalkyl.

[0045] R4 and R5 may be the same substituent or R4 may be H and R5 may not be H at the same time.

[0046] Preferably R6 is C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C6-C 10 Aromatic or C3-C 10 The heterocyclic group is more preferably a C3-C6 cycloalkyl group, a phenyl group, a substituted phenyl group, a naphthyl group, a benzyl group, a pyridine group or a quinoline group; the substituent on the substituted phenyl group is one or more of a C1-C4 alkyl group, a halogen atom or a trifluoromethyl group;

[0047] Preferably, the catalyst described in formula (I) is selected from one of the following formulas a to o:

[0048]

[0049] In the catalytic polymerization reaction, the molar ratio of the cyclopropenium salt catalyst to the substrate is 1:50-20000, preferably 1:200-4000. When there are multiple substrates, the molar ratio of the cyclopropenium salt catalyst to each substrate is 1:200-2000.

[0050] The catalytic polymerization reaction can be carried out in the absence of solvent or in an organic solvent, wherein the organic solvent includes but is not limited to one or more of toluene, dichloromethane, tetrahydrofuran, chloroform, hexane, ether, ethyl acetate, dimethyl sulfoxide, carbon tetrachloride, 1,4-dioxane, preferably toluene, dichloromethane or tetrahydrofuran.

[0051] When an organic solvent is added to the catalytic polymerization reaction, the concentration of all monomers in the substrate is usually 1-10M, preferably 1-8M.

[0052] In the catalytic polymerization reaction, the reaction temperature is 0 to 200°C, preferably 20 to 100°C.

[0053] The reaction time of the catalytic polymerization reaction is preferably 1 to 48 hours.

[0054] After the catalytic polymerization reaction is completed, the reaction solution is post-treated to obtain a polyhydroxyalkanoic acid polymer. The post-treatment method is generally as follows: after the reaction is completed, dichloromethane is added to the reaction solution to dissolve the polymer, and the polymer is added dropwise to a solvent for precipitation, and the polyhydroxyalkanoic acid polymer is obtained after filtration and drying. The solvent can be selected from methanol and n-hexane.

[0055] The cyclopropene salt catalyst can be prepared by the following method:

[0056]

[0057] The amine or phosphine compound represented by formula W1 is reacted with pentachlorocyclopropane or tetrachlorocyclopropene in an organic solvent to obtain a cyclopropene salt organic catalyst.

[0058] The structural formula of the reaction raw material W1 is:

[0059] or H-R3

[0060] The optional structures of Y1, R1, R2 and R3 are as described above.

[0061] Furthermore, it is preferred that the cyclopropene salt catalyst represented by formula (I) is prepared by the following method:

[0062] (1-1) In formula (I), the structure of R3 is -Y2R4R5, and Y2=Y1, R4=R1, R5=R2, that is, the structure of R3 is the same as -Y1R1R2, and is prepared by the following method:

[0063] The compound represented by formula (II) is mixed with pentachlorocyclopropane or tetrachlorocyclopropene, and reacted in an organic solvent to obtain a cyclopropene salt catalyst represented by formula (I-1), wherein X - Cl - ;

[0064] (1-2) In formula (I), the structure of R3 is different from -Y1R1R2, and R 3 Not H, prepared by the following method:

[0065] The compound represented by formula (II) is mixed with pentachlorocyclopropane or tetrachlorocyclopropene, reacted in an organic solvent, and then R3-H represented by formula (IV) is added and the reaction is continued to obtain a cyclopropene salt catalyst represented by formula (I-2), wherein X - Cl – ;

[0066] (1-3) In formula (I), when R3 is H, the compound represented by formula (II) is mixed with pentachlorocyclopropane or tetrachlorocyclopropene, reacted in an organic solvent, and then triphenylphosphine and water are added for reduction, and the reaction is continued to obtain a cyclopropene salt catalyst represented by formula (I-3), wherein X - Cl – ;

[0067]

[0068] (2) For cyclopropenium salts with different anions, namely X - Cl – When the anion is other than - F - Br - ,I - 、NO3 - 、CH3COO - 、CCl3COO - CF3COO - 、Cl2CHCOO - 、PhCOO - , t BuCO - 、CH3CH=CHCOO - 、ClO4 - 、BF4 - ,BPh4 - 、N3 - OH - , p-toluenesulfonate, o-nitrophenoloxy, p-nitrophenoloxy, m-nitrophenoloxy, 2,4-dinitrophenoloxy, 3,5-dinitrophenoloxy, 2,4,6-trinitrophenoloxy, 3,5-dichlorophenoloxy, carbonate, bicarbonate, 3,5-difluorophenoloxy, 3,5-di-trifluoromethylphenoloxy or pentafluorophenoloxy anion, the cyclopropene salt catalyst represented by formula (I-1), (I-2) or (I-3) is subjected to ion exchange reaction with potassium salt KX to obtain the cyclopropene salt catalyst represented by formula (I).

[0069] Cyclopropenium salts with different anions can be obtained by ion exchange of the corresponding cyclopropene chloride salt with anion potassium salt, and the reaction formula is as follows:

[0070]

[0071] In the steps (1-1), (1-2) and (1-3), the molar ratio of pentachlorocyclopropane or tetrachlorocyclopropene to the compound represented by formula (II) is 1:8-10;

[0072] In the step (1-2), pentachlorocyclopropane or tetrachlorocyclopropene is mixed, and the amount ratio of the substance of R3-H represented by formula (IV) is 1:1 to 1.1, preferably 1:1.01 to 1.05.

[0073] In the step (2), the molar ratio of the cyclopropenium salt catalyst represented by formula (I-1), (I-2) or (I-3) to the potassium salt KX is 1:1 to 1.1, preferably 1:1.01 to 1.05.

[0074] Furthermore, in the steps (1-1), (1-2) and (1-3), the reaction temperature is -80 to 150°C, preferably 0 to 80°C.

[0075] The reaction time is 0.1-24 hours, preferably 1-24 hours.

[0076] After the reaction is completed, the reaction solution is returned to room temperature, an aqueous phase is added for extraction, and the organic phase is taken. After removing the organic solvent, a cyclopropenium salt catalyst in which X is a chloride ion is obtained.

[0077] The organic solvent in step (1) can be one or more of tetrahydrofuran, benzene, toluene, chloroform, hexane, ether, dichloromethane, ethyl acetate, dimethyl sulfoxide, carbon tetrachloride, 1,4-dioxane, and pyridine, preferably dichloromethane.

[0078] In the step (2), the ion exchange reaction is carried out in an organic solvent.

[0079] The reaction temperature is 25-100°C, and the reaction time is 2-24 hours.

[0080] After the reaction is completed, potassium chloride precipitates are generated in the reaction solution. The precipitates are removed by filtration, and the organic solvent is removed from the obtained filtrate to obtain cyclopropenium salt catalysts with different anions.

[0081] The organic solvent in step (2) is methanol, ethanol, dichloromethane or tetrahydrofuran.

[0082] Wherein X, Y1, R1, R2 and R3 are defined as above.

[0083] The method of the present invention adopts cyclopropenium salt catalyst, which solves the technical problems of high residual and complicated preparation of traditional metal catalysts; at the same time, in order to solve the technical problems of low catalytic efficiency, low molecular weight and wide distribution of prepared polymers of organic bases, quaternary ammonium salts or quaternary phosphonium salts in the prior art, the present invention develops cyclopropenium salt organic catalyst with ion pair strain. The three carbon atoms on the cyclopropene ion ring are sp 2 Hybridization, sharing two electrons, and the lone pair of electrons of the nitrogen atom in the amino substituent is conjugated with the three-membered ring plane, which can effectively alleviate the instability caused by high ring strain, making the cyclopropene cation one of the most stable carbon cations known. The positively charged ring plane is weakened due to the presence of the amino substituent (which can be understood as an electron-rich cation), resulting in mutual repulsion with the electron-rich coordination ion (this phenomenon is called "ion pair tension"). The electrostatic attraction that is prevalent between anions and cations will be offset by the mutual repulsion between the HOMO orbital of the anion and the high-energy HOMO orbital of the cyclopropene ion. This makes the anion more exposed, so that it can play a better role. In addition, the structure of the cationic part is adjustable, and it is easy to introduce hydrogen bonds of different strengths to activate the lactone monomer and stabilize the chain end during the polymerization process.

[0084] In addition, compared with the traditional lactone ring-opening polymerization process, alkoxy anions or alcohols are often used as initiators (for example, potassium alcohol, benzyl alcohol, etc.) to carry out nucleophilic attack on the carbonyl carbon of the lactone monomer, causing the acyloxy bond to break and open the ring, as shown in the following formula (A).

[0085] The present invention uses halide anions, carboxyl groups and other anions as initiators to perform nucleophilic attacks on the β-carbon of the lactone monomer, causing the alkoxy bond to break and open the ring, as shown in the following formula (B). This ring opening method allows the active chain end to be converted from the alkoxy anion (O-) to the carboxylate (COO-) during the polymerization process, reducing the alkalinity, thereby reducing the ester exchange side reaction that may occur during the chain growth process, further increasing the polymer molecular weight and narrowing the molecular weight distribution. The polyhydroxy fatty acid polymer prepared using the catalyst of the present invention can have a molecular weight of up to 216.7 kg / mol and a molecular weight distribution of up to Compared with the prior art, the molecular weight of the obtained polymer is higher and the molecular weight distribution is significantly narrowed.

[0086] (A)

[0087] (B)

[0088] The cyclopropene salt catalyst provided by the present invention has the advantages of easy weighing, high catalytic activity, controllable reaction, no metal residue in the polymer, etc., fast reaction rate, and the conversion frequency TOF value can be as high as 990h- 1The molecular weight of the obtained polymer can be as high as 216.7 kg / mol, and the molecular weight distribution The catalytic efficiency and yield can be regulated by changing the catalyst concentration, reactant concentration, reaction time, reaction temperature, etc. The method for catalytically preparing polyhydroxy fatty acid polymers provided by the present invention is simple, has high yield, uses less catalyst, and has low cost. The cyclopropene salt organic catalytic system provided by the present invention can effectively synthesize high molecular weight, narrow distribution homopolymer and copolymer materials based on polyhydroxy fatty acids. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 The H NMR spectrum of catalyst 3

[0090] Figure 2 This is the H NMR spectrum of catalyst 5.

[0091] Figure 3 This is the H NMR spectrum of catalyst 6.

[0092] Figure 4 This is the H NMR spectrum of catalyst 13.

[0093] Figure 5 This is the H NMR spectrum of P3HB.

[0094] Figure 6 This is the PPL H NMR spectrum.

[0095] Figure 7 The GPC chart of PPL of Application Examples 22-25 is shown. DETAILED DESCRIPTION

[0096] The technical solution of the present invention is described below through specific embodiments, but the protection scope of the present invention is not limited thereto.

[0097] The catalyst structures and numbers used below

[0098]

[0099] Example 1 Preparation of Cyclopropenium Salt Organic Catalyst 1-3

[0100]

[0101] In an inert gas atmosphere and in an ice-water bath, pentachlorocyclopropane (1.0 mL, 7.79 mmol, 1.0 equiv.) and dichloromethane (20 mL) were added to the reaction flask. After dissolution, diethylamine or di-n-butylamine (8.0 equiv.) was added dropwise to the reaction flask, stirred at room temperature for 18 h, and refluxed at 65 ° C for 5 h to stop the reaction. After cooling, the reaction solution was transferred to a separatory funnel and washed with 2M HCl, deionized water, and saturated NaCl aqueous solution, respectively. The organic phase was removed by vacuum to obtain catalyst 1 or 2.

[0102] Catalyst 2 (0.5 g, 1.0 equiv.) was dissolved in methanol (10 mL), potassium acetate (0.15 g, 1.01 equiv.) was added, and the mixture was stirred overnight. The precipitate was removed by filtration, and the methanol was removed from the filtrate in vacuo to obtain catalyst 3. The H NMR spectrum of catalyst 3 is shown in the attached figure. Figure 1 shown.

[0103] Example 2 Preparation of Cyclopropenium Salt Organic Catalysts 4 and 7-13

[0104]

[0105] Pentachlorocyclopropane (1.0 mL, 7.79 mmol, 1.0 equiv.) and dichloromethane (20 mL) were added to the reaction flask. After dissolution, dicyclohexylamine (8.0 equiv.) was added dropwise to the reaction flask, stirred at room temperature for 18 h, refluxed at 80 ° C for 5 h, and then n-butylamine (1.05 equiv.) was added to the reaction flask and stirred for 5 h. After cooling, the reaction solution was washed with 2M HCl, deionized water and saturated NaCl aqueous solution respectively. The organic phase was removed in vacuo to obtain catalyst 4. The preparation process of catalysts 7 and 9 is similar, except that n-butylamine is replaced with the corresponding benzylamine and aniline.

[0106] Catalyst 9 (1.0 equiv.) was dissolved in ethanol (10 mL), and the corresponding potassium salt (potassium acetate or potassium pivalate or potassium crotonate) (1.01 equiv.) was added, and stirred at 50°C overnight. The precipitate was removed by filtration, and the ethanol was removed from the filtrate in vacuo to obtain catalysts 10-12 respectively. The preparation method of catalyst 8 was similar to this, and catalyst 9 was replaced with catalyst 7, potassium acetate was added, and catalyst 8 was prepared by the same method.

[0107] The preparation method of catalyst 13 is similar to that of catalyst 8, except that benzylamine is replaced by p-fluoroaniline. The H NMR spectrum of catalyst 13 is shown in Figure 4 shown.

[0108] Example 3 Preparation of Cyclopropenium Salt Organic Catalyst 5

[0109]

[0110] In an inert gas atmosphere and in an ice-water bath, pentachlorocyclopropane (1.0 mL, 7.79 mmol, 1.0 equiv.) and dichloromethane (20 mL) were added to the reaction flask. After dissolution, dicyclohexylamine (8.0 equiv.) was added dropwise to the reaction flask, and the mixture was stirred overnight at room temperature. Triphenylphosphine (1.22 g) and water (25 mL) were added to the reaction flask, and the mixture was stirred overnight. The organic phase of the reaction solution was washed three times with deionized water. The organic phase was taken, dried over anhydrous sodium sulfate overnight, filtered, and the organic phase was removed in vacuo to obtain catalyst 5. The H NMR spectrum is shown in FIG. Figure 2 shown.

[0111] Example 4 Preparation of Cyclopropenium Salt Organic Catalyst 6

[0112]

[0113] Add pentachlorocyclopropane (0.23 mL) and dichloromethane (10 mL) to the reaction flask. After dissolution, add dicyclohexylamine (1.4 mL) dropwise to the reaction flask, stir at room temperature for 18 h, reflux at 65 ° C for 5 h, continue to add 25% ammonia water (0.48 mL) to the reaction flask, and stir for 5 h. After cooling, remove the solvent to obtain a solid. Add dichloromethane, filter, and take the filtrate. Remove dichloromethane in vacuo to obtain intermediate (A). Dissolve (A) (0.32 g) in dichloromethane (10 mL), pour into a separatory funnel, extract with 3M NaOH aqueous solution, wash with water and saturated sodium chloride aqueous solution, take the organic phase, dry and remove dichloromethane to obtain intermediate (B).

[0114] (B) (100 mg, 1.0 equiv.) was dissolved in dichloromethane (1 mL), p-tolyl isocyanate (64.37 mg, 2.0 equiv.) was added, and stirred at room temperature overnight. The reaction solution was transferred to a separatory funnel, and 2M HCl, deionized water, and saturated NaCl aqueous solution were added for washing. The organic phase was removed in vacuo to obtain catalyst 6, and the H NMR spectrum was as follows: Figure 3 shown.

[0115] The following are the structures and abbreviations of the β-lactone monomers used in the polymerization

[0116]

[0117] The following copolymerization monomers are used in the structure and abbreviation

[0118]

[0119] The following is an application example of using a cyclopropene salt organic catalyst system to catalyze the homopolymerization of β-lactone monomers and copolymerization with other monomers.

[0120] Application Example 1-21:

[0121]

[0122] In a glove box, add magnetron, catalyst and β-lactone monomer BL to the reaction bottle (if there is a solvent, add the solvent together). Place it in a heated stirrer and stir for a certain period of time. After the reaction is completed, add chloroform solution of benzoic acid to quench. Add dichloromethane to dissolve the polymer, pour the solution into hexane, and precipitate to obtain poly (3-hydroxybutyric acid) (P3HB), the H NMR spectrum is as follows Figure 5 shown.

[0123]

[0124] Application Example 22-35:

[0125]

[0126] In a glove box, add magnetron, catalyst and β-lactone monomer PL to the reaction bottle (if there is a solvent, add the solvent together). Place it in a heated stirrer and stir for a certain period of time. After the reaction is completed, add chloroform solution of benzoic acid to quench. Add dichloromethane to dissolve the polymer, pour the solution into hexane, and precipitate to obtain poly (3-hydroxypropionic acid) (PPL), the nuclear magnetic hydrogen spectrum is as follows Figure 6 The GPC diagrams of Application Examples 22-25 are shown in the attached Figure 7 As shown, the ratios of cyclopropenium salt catalyst to PL monomer are 1 / 500, 1 / 1000, 1 / 2000, and 1 / 4000, respectively.

[0127]

[0128] Application Examples 36-40:

[0129]

[0130] In a glove box, add magnetron, catalyst and β-lactone monomers BL and PL to a reaction bottle (if there is a solvent, add the solvent together). Place it in a heated stirrer and stir for a certain period of time. After the reaction is completed, add a chloroform solution of benzoic acid to quench. Add dichloromethane to dissolve the polymer, pour the solution into hexane, and precipitate to obtain a copolymer of poly(3-hydroxypropionic acid) and poly(3-hydroxybutyric acid) (PBPL).

[0131]

[0132]

[0133] Application Examples 41-45:

[0134]

[0135] In a glove box, add magnetron, catalyst, β-lactone monomer BL and comonomer PO to a high-pressure reactor. Place in a heated stirrer and stir for a certain period of time. After the reaction is completed, add chloroform solution of benzoic acid to quench. Add dichloromethane to dissolve the polymer, pour the solution into hexane, and precipitate to obtain a copolymer of poly(3-hydroxybutyric acid) and epoxide, CO2.

[0136]

[0137] Application examples 46-53:

[0138]

[0139] In a glove box, add magnetons, catalysts, PL monomers and comonomers (if there is a solvent, add the solvent) to the reaction bottle. Place it in a heated stirrer and stir for a certain period of time. After the reaction is completed, add a chloroform solution of benzoic acid to quench. Add dichloromethane to dissolve the polymer, pour the solution into hexane, and precipitate to obtain a copolymer of poly(3-hydroxypropionic acid) and MA (or LA, or PA, NCA, NTA). The reaction formula is as follows:

[0140]

[0141]

[0142] The specific implementation methods described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing polyhydroxyalkanoic acid polymers using a cyclopropene salt catalyst, characterized in that The method is: A cyclic monomer or a cyclic monomer and a small molecule monomer are used as substrates, and a polymerization reaction is carried out under the action of a cyclopropene salt catalyst to prepare a polyhydroxy fatty acid polymer; The cyclic monomer includes at least one or more of four-membered ring β-lactones, and the structural formula thereof is shown in formula (III): Among them, R7, R9, R 10 Each independently selected from hydrogen, unsubstituted or having one or more substituents C: C1-C 18 Alkyl, C1-C 18 Ester group, C3-C 18 Cycloalkyl, C2-C 18 Alkenyl, C2-C 18 Alkynyl, C6-C 18 Aromatic, C3-C 18 Heterocyclic or C5-C 18 A heteroaromatic group; The substituent C is a C1-C10 alkyl group, a C1-C10 alkoxy group, a C3-C10 cycloalkyl group, a C3-C10 heterocyclic group, a C5-C 10 One or more of heteroaromatic groups, C6-C10 aromatic groups; R8 is selected from O, S or NH; The cyclic monomer represented by formula (III) is a racemic, meso or enantiomerically pure monomer; In the method, the chemical formula of the cyclopropene salt catalyst is as shown in formula (I): Among them, X - is a negative ion selected from F - , Cl - Br - ,I - 、NO3 - 、CH3COO - 、CCl3COO - CF3COO - 、Cl2CHCOO - 、PhCOO - , t BuCO - 、CH3CH=CHCOO - 、ClO4 - 、BF4 - ,BPh4 - 、N3 - OH - , p-toluenesulfonate, o-nitrophenoloxy, p-nitrophenoloxy, m-nitrophenoloxy, 2,4-dinitrophenoloxy, 3,5-dinitrophenoloxy, 2,4,6-trinitrophenoloxy, 3,5-dichlorophenoloxy, carbonate, bicarbonate, 3,5-difluorophenoloxy, 3,5-di-trifluoromethylphenoloxy or pentafluorophenoloxy anion or a combination of one or more thereof; Y1 is selected from N or P atoms; R1 and R2 may be independently selected from the following groups which are unsubstituted or have one or more substituents A: hydrogen, C1-C 18 Alkyl, C3-C 18 Cycloalkyl, C2-C 18 Alkenyl, C2-C 18 Alkynyl, C6-C 18 Aromatic, C3-C 18 Heterocyclic or C5-C 18 One or a combination of at least two of the heteroaromatic groups, or R1, R2 and Y1 atoms are connected to form a ring to form a heterocyclic group containing Y1; the substituent A can be one or more of a C1-C10 alkyl group, a C1-C10 alkoxy group, a C3-C10 cycloalkyl group, a C3-C10 heterocyclic group, a C5-C10 heteroaromatic group, and a C6-C10 aromatic group; R1 and R2 cannot be H at the same time; R3 can be selected from the following structures: Wherein, Y2 can be selected from N or P atoms; Z can be selected from O or S atoms; n is an integer of 1 to 10; R4, R5, and R6 may be independently selected from the following groups which are unsubstituted or have one or more substituents B: hydrogen, C1-C 18 Alkyl, C3-C 18 Cycloalkyl, C2-C 18 Alkenyl, C2-C 18 Alkynyl, C6-C 18 Aromatic, C3-C 18 Heterocyclic or C5-C 18 The substituent B may be a C1-C10 alkyl, a C1-C10 alkoxy, a C3-C10 cycloalkyl, a C3-C10 heterocyclic group, a C5-C 10 One or more of heteroaromatic groups, C6-C10 aromatic groups; R4 and R5 cannot be H at the same time.

2. The method according to claim 1, characterized in that In formula (I), R1 and R2 are each independently C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C6-C 10 Aromatic or C5-C 10 Heteroaromatic group, or R1, R2 and Y1 atoms are connected to form a C2-C5 heterocycloalkyl group; R4 and R5 are each independently H, C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C6-C 10 Aromatic or C5-C 10 Heteroaromatic group, or R4, R5 and Y2 atoms are connected to form a C2-C5 heterocycloalkyl group; R6 is C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C6-C 10 Aromatic or C3-C 10 Heterocyclic group.

3. The method according to claim 2, characterized in that R1 and R2 are each independently C1-C4 alkyl, C3-C6 cycloalkyl, phenyl, naphthyl, benzyl, pyridine or quinoline; or R1, R2 and Y1 atoms are connected to form a C5 heterocycloalkyl; R4 and R5 are each independently H, C1-C4 alkyl, C3-C6 cycloalkyl, phenyl, substituted phenyl, naphthyl, benzyl, pyridine or quinoline, and the substituent on the substituted phenyl is one or more of C1-C4 alkyl, halogen atom, trifluoromethyl; or R4, R5 and Y2 atoms are connected to form a C5 heterocycloalkyl; R6 is C3-C6 cycloalkyl, phenyl, substituted phenyl, naphthyl, benzyl, pyridine or quinoline; the substituent on the substituted phenyl is one or more of C1-C4 alkyl, halogen atom and trifluoromethyl.

4. The method according to claim 1, characterized in that The catalyst described in formula (I) is selected from one of the following formulas a to o:

5. The method according to claim 1, characterized in that In formula (III), R7 is H, C1-C5 alkyl, C2-C5 alkenyl or phenoxycarbonyl; R9, R 10 Each is independently hydrogen or C1-C5 alkyl.

6. The method according to claim 1, characterized in that The β-lactone structural formula is one of the following:

7. The method according to claim 1, characterized in that The small molecule monomer is carbon dioxide or carbon monoxide; The cyclic monomers also include cyclic copolymer monomers, and the cyclic copolymer monomers include one or more of oxiranes, cyclothioalkane, cyclic lactones with a ring size greater than four members, cyclolactides, cyclic carbonates, cyclic anhydrides, O-carboxy anhydrides, N-carboxy anhydrides, and thio-N-carboxy anhydrides.

8. The method according to claim 7, characterized in that The cyclic copolymer monomer has one or more of the following structures: Among them, R 11 and R 12 Each is independently selected from the following groups which are unsubstituted or have one or more substituents D: C1-C 30 Alkylene, C3-C 30 Cycloalkylene, C2-C 30 Alkenylene, C2-C 30 Alkynylidene, C6-C 30 Aromatic, C3-C 30 Heterocyclic or C5-C 30 Heteroaromatic group, or the above group containing O, S, N, Si, P atoms in the carbon chain; the substituent D is halogen, a branched or straight chain hydrocarbon group with 1 to 20 carbon atoms, a branched or straight chain alkoxy group with 1 to 20 carbon atoms, a branched or straight chain cycloalkyl group with 3 to 20 carbon atoms, an aromatic group with 6 to 20 carbon atoms, or a heteroaromatic group with 5 to 20 carbon atoms; Among them, R 13 Selected from H, halogen, unsubstituted or having one or more substituents E: C1-C 30 Alkyl, C3-C 30 Cycloalkyl, C2-C 30 Alkenyl, C2-C 30 Alkynyl, C6-C 30 Aromatic, C3-C 30 Heterocyclic or C5-C 30 The substituent E is one or more selected from halogen atoms, branched or straight-chain hydrocarbon groups having 1 to 20 carbon atoms, branched or straight-chain alkoxy groups having 1 to 20 carbon atoms, branched or straight-chain cycloalkyl groups having 3 to 20 carbon atoms, aromatic groups having 6 to 20 carbon atoms, and heteroaromatic groups having 5 to 20 carbon atoms.

9. The method according to claim 8, characterized in that R 11 , R 12 is C1-C4 alkylene, C2-C3 alkenylene, C3-C6 cycloalkylene or phenyl; R 13 It is H, halogen, C1-C5 alkyl, C2-C4 alkenyl, C3-C6 cycloalkyl or phenyl.

10. The method according to claim 1, characterized in that In the catalytic polymerization reaction, the molar ratio of the cyclopropene salt catalyst to the substrate is 1:200-20000; the catalytic polymerization reaction temperature is 0-200° C.; the catalytic polymerization reaction can be carried out without solvent or in an organic solvent; and the catalytic polymerization reaction time is 1-48 hours.

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